Today, personal computers are usually equipped with a computer mouse, which is used for positioning a cursor on the computer screen. The positioning is carried out by the user passing the mouse over a surface, the hand movement thus indicating how the mouse should be positioned. The mouse generates positioning signals indicating how the mouse is being moved and thus how the cursor should be moved. For this purpose, the mouse usually has a track ball, which turns as a result of friction against the surface when the mouse is passed over the same and which in this connection drives position sensors which in turn generate the positioning signals. Normally, the mouse can also be used for providing instructions to the computer by the intermediary of one or more buttons on which the user clicks. However, when the term “mouse function” is used below it only refers to the function of positioning a cursor or the like.
To input text and images into a computer a hand-held scanner is sometimes used, which images the text or image which is to be input with the aid of a light-sensitive sensor. The scanner can only image a very limited text/image area at one time. Consequently, in order to record one or several words or a whole image, the scanner must be passed over the text/image and several sub-images must be recorded. Usually, the scanner has some kind of position sensor which determines how these sub-images should be stored in the computer to enable the creation of a composite image therefrom.
It is known to combine a mouse function and an inputting function in a casing which is connected with a single flex to a computer.
U.S. Pat. No. 4,906,843, for example, shows a combined mouse, optical scanner, and digitising pad. In the mouse mode, a track ball is used, which drives two position sensors, which generate the positioning signals. In the scanner mode, a CCD line sensor as well as the position sensors are used for inputting characters or graphical information to the computer.
U.S. Pat. No. 5,355,146 shows a similar input unit with a combined mouse function and scanner function, which also utilises a track ball and a CCD line sensor.
EP 0 782 321 shows yet another input unit having a mouse function and scanner function. In this case, too, a track ball is used for the mouse function but instead of the line sensor, use is made of an area sensor which is capable of imaging a document in a single step and which thus need not be moved across the document. This is said to have the advantage that no software is required for correlating image data with position data.
U.S. Pat. No. 5,633,489 shows a combined mouse and barcode reader, where the mouse function is provided by means of a track ball and the barcode reader comprises a laser diode which generates a laser beam emitted from the underside of the mouse and a photo detector which detects the varying intensity of the reflected light.
All these known input units have a rather complicated mechanical design with moving parts and many sensors. Moreover, they only provide limited synergies between the functions combined in one and the same casing.